The first paragraph suggests the order is for “targeted and personalised information”.

That would suggest that it's unlikely to be anonymised data collection; at best perhaps pseudonymous... and then you get into the questions about how easy it is relate these ids to real identities. Let's hope Facebook stays out of the equation with their fr and c_user cookie fields.

The intentions may be well meaning (let's optimise services for businesses and people prior to significant changes). However, we've recently had the Windrush scandal and Home Office hostile environment policy: there are over a million people in the UK who may have questions about their residence rights changing and wouldn't like to be tracked whilst they try to find answers.